Electroplating of nickel



Patented Aug. 11, 1953 ELECTROPLATING OF NICKEL Henry Brown, Detroit, Mich., assignor to The Udylite Corporation, Detroit, Mich, a corporation of Delaware No Drawing. Application July 17, 1950, Serial No. 174,375

12 Claims. (01. 204-49) My invention relates to improvements in the electro-deposition of nickel from aqueous acidic baths. It is particularly concerned with the utilization of mixtures of certain types of agents for the purpose of decreasing grain size and increasing the luster of the nickel plate or deposit, and it is especially concerned with the production of electrodeposits of brilliant, highly lustrous, ductile nickel plates.

I have discovered that the above highly desired results are achieved through the conjoint utilization, in the nickel plating bath, of one or more agents of the type exemplified in the following Table I, in conjunction with one or more agents of the type exemplified in the following Table II.

The agents of Table I are illustrative of the class of compounds, found to be useful in the practice of my present invention, in accordance with the formula where zero, 1 or 2, the compounds can contain one or two nuclear halogen groups or, where x is zero, the nucleus is unsubstituted.

Excellent results are obtained with compounds where a: is zero;

or where R is chlorine or bromine and a: is 1. Of outstanding utility are Z-methyl quinoline and 3-methyl isoquinoline. Good results are also obtained with quinoline, isoquinoline, and 2,6- dimethyl quinoline or mixtures of any two or more thereof, or mixtures of 2-methyl quinoline with one or more of the other compoundsdisclosed hereinf It will be understood, of course, that pure or commercial sources of said compounds can be employed and, ingeneral, commercial sources of certain of said compounds will usually be found to contain minor proportions of others of said compounds. Thus, for example, commercial Z-methyl quinoline ordinarily contains about 5% isoquinoline.

TABLE I Optimum Quinolme and Isoqmnolme Compounds Gone,

' Grams/liter l. Quinoline 005-. 02 2. Isoquino1me .003-.02 3. 2-metl1yl qumohm..- 005-. 03 4. S-iodo quinollne 005-. 03 5. 2,6-dimethy1 quinoline .005.03 6. 2-chloro quinoline .005-.03 7. 6 bromo quinoline 005-..03 8. S-methyl qumohne i 005-. 03 9. 2,4;6-tn'ruethyl quinoline 005-. 03 10. Z-ethyl quinofine 005-. 02 ll. 2-bromo quin0line 005-. 03 12. fi-bromo isoquinolme. 003-. 02 13. (S-methyl isoquinoline. .'003. 03 14. 2,4-dibromo quinoline 005-. 03 15. 2,4-dichloro quinoline 005-. 03 .16. 2,8-dimethyl guinqline. 005-. 03 17. 1,3-dimetl1yl1soqumol1ne .003 02 18. 3-methyl isoquii'ioline. 003-. 03 19. 2-methyl-8-bromo quinoline. 005-. 03 20. 2-,metl1yl-8-ch10r0 quinoline 005-. 03 21. 3-chloro-2-methyl quinoline. .005-. 03 22. 8-bromo-2-metl1y1 quinoline 005-. 03 23. l-methyl isoquinoline .003. 03

The agents of Table II are illustrative of the class of compounds which are employed in conjunctionwith the agents of'Table I, in the practice of my invention. The agents of Table II, it will be noted, fallinto thecategory of organic sulfonamides, sulfonimides and sulfonic acids. They have heretofore been used as brighteners in nickel plating baths as is disclosed in part, for example, in my prior Patents Nos. 2,191,813

3 and 2,466,677. In the practice of my present invention, a coaction takes place in the cathode film, the exact nature of which is unknown, involving the compounds of the type shown in Table I and the organic sulfur-containing brightener which produces the unusual and highly important results which are brought about in accordance with my invention. In this connection, it may be noted that the utilization alone of the agents or compounds of the type shown in Table I, or the utilization alone of the organic sulfur-containing brighteners, gives no indication of the remarkably enhanced results which occur when both types of compounds are present in the bath, particularly when utilized in their optimum concentrations. In general, it is desirable to use mixtures of two or more of said sulfur-containing brighteners as, for example, o-benzoyl sulfimide and p-toluene sulfonamide;

and allyl sulfonic acid and benzene sulfonamide.

TABLE II Ogtimum onc., Sulfur-Containing Bnghteners Grams,

liter 1. Benzene sulfonamide 0. 1-3 2. Toluene sulfonamides (oand p-) 0. 1-2 3. o-Benzoyl sulfimide 0. 1-2 4. N-Benzoyl benzene sulfonimide 0. l-1 5. p-Toluene sulfonchloramide 0. 1-1 6. p-Brom benzene sulionamida. 0. 1-1 7. (i-Ghlor o-benzoyl sulfimide 0. 1-1 8. m-Aldehydo benzene suli'onamide O. l-l 9. Sulfcmethyl benzene sulfonamide 0. 1-6 10. Benzene sulionamide m-carboxylic amide 0. l-3 11. 7-Aldehydo o-benzoyl sulfimide 0.1-3 l2. N-Acetyl benzene sulfonimide 0. 1-2 13. Methoxy benzene sulfonamides 0. 1-1 14. Hydroxymethyl benzene sulfonami 0. 1-2 15, Vinyl snlfmnmide 4-12 16. Allyl sulionamide i-12 17. Benzene sulfonic acids (mono-, di-, and tri-) 1-15 18. p-Brom benzene sulfcnic acid 3-6 19. Benzaldehyde sulionic acids (0, m, p) 2-6 20. Diphenyl sulfone sulfonic acid 1-8 21. Naphthalene sulfonic acids (mono-, di-, and tri-) 1-8 22. Benzene sulfohydroxamic acid 1-5 23. p-Ohlor benzene sulfonic acid..." l-l 24. Diphenyl sulfonic acid 1-5 25. m-Diphenyl benzene sulfonic aci 1-4 26. Z-Chloro-5-sulfobenzaldehyde. 1-5 27. n'i-Benzene disulfonamide 0.5-1 28. Allyl sulfonic acid 4-12 It will be understood that said sulfonic brighteners may be utilized in their acid form or in the form of salts as, for example, nickel, sodium, potassium or other salts. Especially satisfactory, for use in the practice'of my present invention, are the compounds of Table II corresponding to numbers 1, 2, 3; 1s, 19, 21 and 2a, the latter particularly in the form of their nickel salts.

Where the term sulfonic acids is used herein and in the claims, it will be understood that the salts thereof are likewise included.

The compounds of Table 11, used alone, produce reasonably bright deposits on buffed metals such as bufied brass. However, at least in the ordinary case, they do not accomplish the same dark, brittle, easily stained and have poor adherence characteristics at higher concentrations. If, however, the two different types of compounds represented in Tables I and II are used together in the baths, as I have indicated above, brilliant mirror-like, adherent and ductile deposits are obtained even over matte surfaces.

Only small proportions of the compounds, or mixtures thereof, of Table I are necessary to achieve the aforesaid results. portions in the range of about 0.003 gram/liter to about 0.04. gram/liter of any of the compounds or mixtures thereof will be most effective in the usual case although, particularly with the more efiicacious ones of the compounds, proportions even as low as about 0.001 gram/liter give good results. Even in the case of the less effective Jones of the compounds, it is rarely necessary to exceed about 0.04 gram/liter. As a general rule, the optimum concentration of the compounds ,will be found to fall within the range of about results on steel polished with 180 emery or on matte (but unburnt) copper plate of 0.0003- '0.0005 thickness but, rather, generally yield plates of somewhat dull and gray appearance in these cases. The compounds of Table I, in the usual case, when used alone, give a different type of plate than that produced by the compounds of Table II. The plates produced with the compounds of Table I alone are fine grained and cloudy at very low concentrations, and are rather 0.005 to about 0.03 gram/liter.

The compounds of Table II are likewise used in small proportions, in conjunction with the compounds of Table I, amounts of the order of about 0.1 gram/liter to 2 or 3 grams/liter being effective in the usual case. Higher proportions, up to saturation, can, however, be utilized. Ordinarily, it is unnecessary to exceed about 0.5%.

The optimum concentration of the compounds of Tables I and II in any specific instance may readily be determined by simple test in the light of the particular nickel bath utilized, its temperature, its pH, etc.

The aqueous nickel plating baths may be of various types but, in all cases, they are acidic in character. The preferred baths are of the socalled acidic grey type which are capable of producing thick, adherent, ductile deposits, those of the Watts type or modifications thereof being particularly desirable. The nickel salts may comprise nickel chloride, nickel sulfate, nickel fluoborate, nickel sulfamate, or other nickel salts or mixtures of any two or more of said nickel salts, preferably in conjunction with bufier materials as, for example, boric acid. I prefer to utilize boric acid in the bath as it is, in general, the best cathode film buffer. Other buffers of acidic character may, however, be employed as, for example, formic acid, citric acid, fiuoboric acid, and the like, and such may be used either in place of or in conjunction with boric acid. For optimum results, the concentration of the boric acid or its equivalent should be above 30 grams per liter, especially in baths operated at somewhat elevated temperatures. The baths may also contain various supplemental agents such as anti-pitting agents and the like.

The baths can be operated at temperatures ranging from about room temperature to almost boiling but, in general, the preferred temperature is in the range of about 40 degrees C. to 65 degrees C. In general, the baths can be operated at pH values ranging from about 2 to about 5.5

but, in'the ordinary case, the preferred pH values are from 2.5 to 4.8. The cathode current density ranges are quite variable, a range of about 5 to several hundred amperes per square foot being utilizable, the optimum depending upon agitation,

temperature, and. concentration and type of nickel salts utilized in the bath. A good working range is about 20 to about amperes per square foot. In Table III, I list preferred embodiments of bath compositions.

Generally, pro- TABLE m Grams/liter Grams/liter g gg fg gi Temperature, F. PH

1.-.-.--. 200 to 300...- 45 40 75to160-.. 2to6 10 to 75.... {g'

2- 300 40 75 t0160... 1 to 5....-. to 100...

3....-.--- 50 to 200..... 100 to 250.... 75 to 160... 1.5 to 6...- 10 to 85....

-benzoyl sulfimide-l. 2-methyl quinoline.003 to. .02. Quinoline.003.

Benzene sulfonam1de2. o-benzoyl sulfimide-2. B-methyl quinoline.0l5. p-toluene sulfonamide1.5. o-benzoyl su1fimide0.l.

4 200m 300.... to 75 4to8 40 to 50.... 75to160... 2m 10 to 15....

5 200 to 300.... 45 to 100..... 8 to 50..." 40 to sat... 75 to 160...

6 to 100.. 45 to 100..... 8 to 100.... 40 t0 sat..- 75 to 160... 2 to 6 10 to 85....

3 200 to 250.-.. 100 to 150-... 8 to 15..... 40 to 50.... 75 to 160... 2 t0 6 10 to 85..--

50 to 150... 40 to sat... 75 150160... 2 t0 0-..... 10 t0 100...

Bfinzene sulfonarglidc 7264 t 02 2- romo isoquino ine. 0 2 to 6 10 to {o-benzoyl sulfimide2.

2-methy1 quinoline.005 to .03. o-benzoyl sulfimide-l. p-toluene sulfonamide-l. 3-mcthyl isoquino1ine.003 to .02. o-benzoy1su1fimide1. I Benzene sulfonamide1. 2-methyl quinoline.003. Quinoline.002. o-Benzaldchyde sulfonicacid-3 to 8'.

9 100 to 300.. 0mm-.. 75 to 100... 41:05 10 to 200.; {itdimethyl 11 100 to 200..-- 200 to 100..-. 40 110 to 140.. 3 to 4.5..-. 40 to 60....

N apthalene sulfonic acids.3 to 6.

110 to 140.. 3 to 4.5.... 40 to 60.--- {333 5 5.9553

o-benzoyl sulfimidel. p-toluene sulfonamide-l.

Quinoline-.O05 to 015 12 300 so 40 70 to 160..- 2.5 to 4.8... 40 to com- 2methY1qum1me -05 13 225 '50 to 76 40 70 to 160... 2.5 to 4.8... 40 to 60....

. p-toluene sulionamide-d to 2.

o benzoyl sulfimide-l to 3. Isoquinoline.006.

Z-methyl quinoline-. 015. Benzene sulfonarnide-2. o-benzoyl sulfirmde-Z.

It will be understood that, from time to time, it is necessary to replenish the bath to rep-lace losses due to cathodic processes, to drag-out, and to other causes, in order tomaintain the concentrations of the added compounds, etc. in operative proportions.

This application is a continuation-impart of my application Serial No. 587,427, filed April 9, 1945, said latter application being, in turn, a continuation-in-part of my application Serial No. 366,386, filed November 20, 1940, all of said applications being now abandoned.

What I claim as new and desire to protect by Letters Patent of the United States is:

1. A bath for the electrodeposition of bright nickel comprising an aqueous acidic solution containing at least one nickel salt selected from the group consisting of nickel chloride and nickel sulfate, said bath also containing, in solution, not more than 1 5 grams per liter of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides, and sulfonic acids, and, in addition, from about 0.005 to about 0.04 gram per liter of a bath-soluble compound in accordance with the formula where represents a compound selected from the group consisting of guinoline, isoquinoline and C-methyl and ethyl homologues thereof, R is halogen, and .z: is zero to 2.

2. A bath for the electrodeposition of bright nickel comprising an aqueous acidic solution of at least one nickel salt, said bath also containing. in solution, not more than about 15 grams per liter of at least onebrightener selected from the group consisting of organic su1fonamides,.sulfonimides, and sulfonic acids, and, in addition, .005-.04 gram per liter of Z-methyl quinoline.

3. A bath for the electrodeposition of bright nickel comprising an aqueous acidic solution containing at least one nickel salt selected from the group consisting of nickel, chloride and nickel sulfate, said bath also containing, in 5010mm, not more than about 15 grams per liter of at least one brightenerselected from the group consisting of organic sulfonamides, sulfonimides, and .sulfonic acida'and, in addition, from about 0.005 to about 0.04 gram per liter of Z-methyl quinoline.

4. A bath for the electrodeposition of bright nickel comprising an aqueous acidic solution con,- taining at least one nickel salt selected from the group consisting of nickel chloride, and nickel sulfate, said bath also containing, in solution, not more than about 15 grams per liter of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimidea. and sulfonic'acids, and, in additiomfrom about 0.005 to about 0.04 gram per liter of a bath-soluble compound in accordance with the formula 0.04 gram per liter of a mixture of isoquinolineand 2-methyl quinoline.

6. A bath in accordance with claim 1, wherein the compound is isoquinoline.

7. A bath in accordance with claim 1, wherein the compound is a C-methyl quinoline.

8. A method of electrodepositing nickel to obtain a fine-grained, ductile deposit of high brilliance which comprises electrolyzing an aqueous acidic solution containing at least one nickel salt selected from the group consisting of nickel chloride and nickel sulfate, said bath also containing, in solution, not more than about 15 grams per liter of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides, and sulfonic acids, and, in addition, from about 0.005 to about 0.04 gram per liter of a bathsoluble compound in accordance with the formula represents a compound selected from the group consisting of quinoline, isoquinoline and C- methyl and ethyl homologues thereof, R. is halogen, and :1: is zero to 2.

9. A method of electrodepositing nickel to obtain a fine-grained, ductile deposit of high brilliance which comprises electrolyzing an aqueous acidic solution of at least one nickel salt, said bath also containing, in solution, not more than about 0.5% of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides, and sulfonic acids, and, in addition, from about 0.005 to about 0.04 gram per liter of Z-methyl quinoline.

10. A method of electrodepositing nickel to obtain a fine-grained, ductile deposit of high brilliance which comprise electrolyzing an aqueous acidic solution containing at least one nickel salt selected from the group consisting of nickel chloride and nickel sulfate, said bath also containing, in solution, not more than about 5% of at least one brightener selected from the group consisting of organic sulfonamides, sulfonimides, and sulfonic acids, and, in addition, .005-04 gram per liter of a bath-soluble compound in accordance with the formula 8 where R is a halogen selected from the group consisting of chlorine and bromine, and a: is zero to 2.

11. In a bath for the electrodeposition of bright nickel comprising an aqueous acidic solution containing at least one nickel salt selected from the group consisting of nickel chloride and nickel sulfate, an additive for use in an amount of about .005 to about .04 gram per liter in combination with at least one brightener selected from the group consisting of organic sulfonamides,sulfonimides and sulfonic acids in an amount of not more than about 15 grams per liter in said bath, said additive consisting of a compound having the formula represents a compound selected from the group consisting of quinoline, isoquinoline and C-methyl and ethyl homologues thereof, R. is halogen, and a: is zero to 2.

12. An additive for an aqueous acidic solution containing at least one nickel salt selected from the group consisting of nickel chloride and nickel sulfate and at least one brightener selected from the group consisting of sulfonamides, sulfoninlides and sulfonic acids in an amount of not more than about 15 grams per liter in combination with said additive in an amount of about .005 to about .04 gram per liter, said additive consisting of a compound having the formula where References Cited in the file of this patent UNITED STATES PATENTS Name Date Lind et al Apr. 15, 1941 Lind et a1 Apr. 6, 1943 CTHER REFERENCES Raub et al., Metal Finishing, August 1940, pp. 429-432.

Number p T wa 

1. A BATH FOR THE ELECTRODEPOSITION OF BRIGHT NICKEL COMPRISING AN AQUEOUS ACIDIC SOLUTION CONTAINING AT LEAST ONE NICKEL SALT SELECTED FROM THE GROUP CONSISTING OF NICKEL CHLORIDE AND NICKEL SULFATE, SAID BATH ALSO CONTAINING, IN SOLUTION, NOT MORE THAN 15 GRAMS PER LITER OF AT LEAST ONE BRIGHTENER SELECTED FROM THE GROUP CONSISTING OF ORGANIC SULFONAMIDES, SULFONIMIDES, AND SULFONIC ACIDS, AND, IN ADDITION, FROM ABOUT 0.005 TO ABOUT 0.04 GRAM PER LITER OF A BATH-SOLUBLE COMPOUND IN ACCORDANCE WITH THE FORMULA 